1. Field of the Invention
The preset invention relates to a processing system including a machine tool and a robot, and having a function for maintaining a processing accuracy of the machine tool.
2. Description of the Related Art
In a conventional machine tool, in order to check an abrasion status of a working tool, it is necessary for an operator to measure dimensions, etc., of the working tool. In this regard, the life of the tool varies depending on a cutting condition, and thus it takes many man-hours to check an amount of abrasion with respect to each workpiece or each cutting condition, and correct the next processing program based on the checking result. In fact, in many cases, an upper limit of operating time of the processing tool is determined based on a life of the processing tool experimentally obtained from an operation result at a certain cutting condition, and the processing tool is replaced with a new processing tool when the operating time of the tool reaches the upper limit of operating time.
As relevant prior art documents, JP H09-085584 A discloses a technique to judge as to capture a tool to be used next time by a capture means, identify the tool from a captured tool image data by a tool identifying part, and judge as to whether or not the tool identified by the tool identifying part coincides with a tool previously specified in an NC program.
JP 2002-018680 A discloses a machine tool having a processing tool, a camera for capturing an image of the tool, and an image processing part for judging as to whether or not the tool is damaged based on the image captured by the camera.
JP H10-096616 A discloses a system intended to automatically detect abrasion or breakage of a tool chip attached to a machine tool in a non-contact manner, and describes that the tool tip may be inspected either when the tool is attached to the machine tool or when the tool is removed from the machine tool. In the latter case, by using a robot for moving the tool to an inspection position and a robot for supporting a light projector and an imager of a vision sensor, breakage inspection and exchange of the tool tip can be automated.
JP H07-156067 A discloses a device for correcting an amount of abrasion of a grinding tool of a grinding robot, and describes that, when a grinding wheel contacts an object to be grind at various angles so as to grind the object, an abrasion status of the grinding wheel is directly detected by using a light section image and profile information before and after the abrasion, an amount of abrasion of the grinding wheel is calculated with respect to each inclined posture of the wheel, and a corrected amount of abrasion is calculated corresponding to the amount of abrasion, whereby the grinding position of the wheel during the grinding operation can be precisely corrected.
JP 2014-075050 A discloses a processing system having a measurement robot for measuring the shape of a workpiece, and describes that the measurement robot measures the shape of the next workpiece during the current workpiece is machined by a processing machine, and thus the measurement robot can be effectively used so that measuring and machining are carried out in parallel.
JP 2011-045988 A discloses a capturing means arranged in a machine tool, and a means for correcting a processing position of a cutting tool by calculating an amount of abrasion and an amount of displacement of the cutting tool based on image data obtained by capturing the cutting tool.
Further, JP 2001-150299 A discloses a tool life management device having: a keyboard for setting a life length of a tool; a measurement probe for measuring a length of a tool attached to a machine tool; a CPU for judging a life of the tool based on the set life length and the measured tool length; and a CRT for displaying life information of the tool based on the judgment result of the CPU.
In the conventional machine tool, it is not realized that the amount of abrasion of the tool is recognized in the machine tool so as to automatically correct the processing program. One of the reasons therefor is that it is difficult to arrange a sensor such as an image processor and a contact sensor, etc., for measuring the amount of abrasion of the tool, while assuring reliability of the sensor, under an environment in which cutting fluid always pours on the sensor.
Therefore, in the conventional method, an allowable amount of abrasion (or a life) of the tool is predetermined within a functionally allowable error range, and the tool is replaced with a new tool when the actual amount of abrasion of the tool reaches the allowable amount of abrasion. Therefore, processing accuracy is deteriorated with time, and in the worst case, processing defect may occur at the time when the tool almost comes to the end of its life, whereby the processed workpiece cannot be used. In addition, the degree of abrasion and the life of the tool may be significantly varied depending on the material of the workpiece and the cutting condition, and thus it is difficult to precisely calculate the life of the tool unless the processing is actually carried out.
In the technique of JP H09-085584 A or JP 2002-018680 A, the image of the tool is not obtained by the robot, and the processing program of the machine tool is not corrected. Also, in the technique of JP H10-096616 A, the processing program is not corrected.
In the invention of JP H07-156067 A, the motion program of the robot, which is different from the processing program of the machine tool, is corrected. Further, in the invention of JP 2014-075050 A, although the image of the workpiece to be processed is obtained, the image of the tool is not obtained.
The technique of JP 2011-045988 is intended to correct the processing position of the processing tool, but is not intended to use the robot. Further, although JP 2001-150299 A describes that the life information of the tool is displayed, this document does not mention the calculation of remaining possible processing time or a number of remaining possible processing operations for the tool.